Magnetic blow-out for circuit-breakers



March 15, 1955 A. R. NORDEN MAGNETIC BLOW-OUT FOR CIRCUIT-BREAKERS Filed Dec. 18, 1951 .M RR a m. m4 M p n. M M 4 United States Patent MAGNETIC BLOW-OUT FOR CIRCUIT-BREAKERS Alexander R. Norden, New York, N. Y., assignor to Federal Electric Products Company, Newark, N. 1., a corporation of Delaware Application December 18, 1951, Serial No. 262,221

Claims. (Cl. 200-147) This invention relates in general to circuit breakers and more particularly to magnetic blow-outs for circuit breakers which are disposed within enclosures or casings therefor.

One object of the invention is to provide an enclosed circuit breaker with means to prevent or minimize damage to or impairment of the circuit breaker mechanism by arcs which may be formed during the operation of the circuit breaker for opening the circuit under load.

Another object is the provision, in an automatic circuit breaker having a casing provided with an arcing chamber which has communication through the easing to the exterior thereof, of generally improved means for impelling arcs away from the circuit breaker mechanism and through said chamber to the exterior of said casing.

A further object is the provision of arc blow-out means of generally improved construction and operation for extinguishing an are between the separable contact elements, said means being of simple, durable and inexpensive construction.

A still further object of the present invention is the provision of magnetic blow-out means for the separable contacts of a circuit control device which means is relatively small in size and easily mounted within a limited space.

The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings:

Fig. 1 is a side view of a circuit breaker embodying the present invention, one part of the casing be ing removed and the circuit breaker mechanism being in the closed condition thereof;

Fig. 2' is a view similar to Fig. 1, showing the circuit breaker mechanism in the open condition thereof;

Fig. 3 is a sectional view taken on the line 3-3 of Pi 2' iigj 4 is an end view of the circuit breaker taken in the direction of the arrow 4 in Fig. 1;

Fig. 5 is a view of a blow-out member according to the present invention; and

Fig. 6 is a substantially diagrammatic view illustrating the operation of the present invention.

Referring now to the drawings in detail, there is illustrated an automatic circuit breaker 10 which is generally similar in construction to that described and claimed in U. S. Patent Re. 23,188, issued January 10, 1950, to H. A. Humpage and assigned to the assignee hereof. Said circuit breaker is provided with a two part insulation housing or casing 12 formed by the body part 14 and the complementary closure part or cover 16, said parts being secured in housing-defining relation in any suitable way. Said body part 14 is provided with a wall portion 17 which separates the chambers 18 and 20 defined therein. Said wall portion is recessed, as at 19, to form a passage-way between the chambers. The circuit breaker mechanism, as hereinafter described in detail, is mounted within the chamber 18, the chamber 20 constituting an arcing chamber or are chute which is provided with a vented passage-way 22 which communicates with the exterior of the casing as at 24. A load terminal 26 is 2,704,315 Patented Mar. 15, 1955 ice mounted, in any suitable manner, in an open recessed portion 28 of the casing and is provided with a stationary contact 30 which is disposed within the arcing chamber 20 for releasable engagement by a companion movable contact 32 which is carried by the movable contact member 34 of the circuit breaker mechanism. Said movable contact member is pivotally mounted, as at 36, within the chamber 18 and is provided with an end portion 40 which extends into the-arcing chamber 20 through the passage-way 19, and carries the previously mentioned movable contact 32.

Pursuant to the present invention, provision is made in the arcing chamber 20 for magnetic blow-out means constituted by the magnetizable member 42, preferably made of magnet core material. More specifically, said member 42 is substantially right-angular in formation being provided with a horizontally disposed portion 44 and with the vertically disposed portion 46. As here shown, the casing part 14 is provided with the integral portions 48 and 50 which extend into the arcing chamber and constitute baflles therefore. The blow-out member 42 is conveniently mounted in the arcing chamber by being disposed between the baffie 48 and the opposing wall portion 52 of the casing part 14. Therefore, it will be readily apparent that when the cover 16 is secured to the casing part 14 the blow-out member 42 is retained in said position solely by the casing parts.

Referring to Figs. 3 and 5, it will be noted that the horizontally disposed portion 44 of the blow-out membet is provided, at the free end thereof, with the substantially semicircular cut-out or half-turn portion 54 to provide magnetic poles of opposite polarity, respectively, at the end portions 56 and 58 when said mem' her is magnetized, as hereinafter described in detail. Referring now to Figs. 2 and 3, it will be noted that the stationary contact 30, while preferably disposed above the member 42, is substantially intermediate the poles 56 and 58 in a vertical plane laterally offset from said member. Therefore, it will be understood that when the movable contact 32 disengages the companion stationary contact 30 the former will travel along a path which extends substantially between said poles although offset outwardly thereof.

Upon the occurrence of an overload or other abnormal current condition in the circuit controlled by the circuit breaker 10, the movable contact 32 will be carried out of engagement with the stationary contact 30, the mechanism moving from the closed position thereof illustrated in Fig. 1, to the open position thereof illustrated in Fig. 2. Upon separation of the contacts, the space therebetween defines arc-gap across which the current may continue to flow between the contacts to generate an arc, as indicated in broken line at 60 in Fig. 2, wherein an intermediate position during the travel of the movable contact 32 is also illustrated in broken line. Said arc, being essentially a conductor of current, Will generate a magnetic field thereabout, as in the case of current flow through any conductor of current, as is well known to those skilled in the art.

Referring now to Fig. 6, and assuming that the current flow through the arc is in a direction outwardly of the drawing, as indicated on the conductor 62 in Fig. 6, which is representative of the are 60, it will be apparent that the magnetic flux or lines of force resulting from said current flow will be in the counter-clockwise direction indicated by the arrows 64. The magnetic field about the arc will be effective to magnetize the magnetizable member 42 and create magnetic lines of force or flux between the magnetic poles 56 and 58 which will flow from pole 58 to pole 56, as indicated by the arrows 66. It will be noted that the lines of force of both magnetic fields, in the area inwardly of the current conductor 62 and adjacent the blow-out member 42, will oppose each other and thereby tend to cancel each other, Whereas the lines of force of said fields outwardly of the conductor 62 and away from the member 42 will be in the same direction and therefore reinforce each other. Therefore, it

will be apparent that the resultant magnetic motion or force will be in the direction of the arrow 68, namely, toward the blow-out member 42. As is well known to those skilled in the art, said resultant magnetic force will blow the are outwardly from the contacts into the arcing chamber 20 and away from the chamber 18 in which the circuit breaker mechanism is housed.

The are being blown toward the member 42 will bow and be elongated whereby to hasten the attenuation thereof and in addition by being blown against the cool metallic surfaces of the member 42, the arc and the hot gases generated thereby will be cooled and thereby hasten the extinction of the arc. Moreover, due to the right angular formation of the member 42, the arc will be guided downwardly along the vertical portion 46 thereof, and at an angle to the outward movement thereof, toward the passage-way 22 and the hot gases will be expelled from the opening 24. In this connection, it will be noted that the free end of the vertical portion 46 is at the entrance to said passage-way.

When the direction of current flow through the circuit breaker is the reverse of that illustrated in Fig. 6, so that the current will flow into the drawing, it will be apparent that the direction of the previously described magnetic fields also will be reversed. The magnetic field about the conductor 62 will now be clock-wise and the magnetic lines of force in the member 42 will now flow from the pole 56 to the pole 58. However, it will be readily apparent that the resultant magnetic field will still be in the direction of the arrow 68 for attenuating and cooling the are.

In order to provide for the tripping of the circuit breaker mechanism upon the occurrence of an overload or other abnormal current condition in the circuit controlled thereby, the movable contact member 34 is provided, as here shown, with a thermostatic bi-metallic flexible strip 70, one end of which is secured thereto in any suitable manner. The free end of strip 70 is arranged to releasably engage the actuator or latch 72 which is pivotally mounted on the movable contact member, as at 74. A resilient link 76 inter-engages the latch 72 and one end 78 of a pivotally mounted handle 80 which extends through an opening 82 provided in the casing. A coil compression spring 84 is operatively interposed between the movable contact member 34 and handle 80 for biasing the movable contact member to its open position. handle 80, the movable contact member 34, the thermostatic strip 79, the lever or actuator 72 and the link 76 is similar to and operates substantially in the same way patent.

The mechanism constituted by the It will be understood that the strip 70 operates to latch the manually operable actuator 72 to the movable contact member 34 and to unlatch said actuator from the movable contact member, the unlatching taking place upon deflection of the strip 70, causing the disengagement actuator, the spring 84 is effective to move the contact A member 34 to its open position, that is from the position illustrated in Fig. l to the position illustrated in Fig. 2.

The thermal element is connected in series with the movable contact member 34 and the circuit which is to be controlled by the circuit breaker. For this purpose, and as here shown, a flexible metallic connector 86 is connected between the said thermal element and a stab or plug-in contact 88 which is adapted to be received in a complementary terminal, for example, as

illustrated and described in the United States application, Serial No. 127,432 filed November 15, 1949, by T. M. Cole and P. M. Christensen, now Patent No. 2,647,225, issued July 28, 1953, and assigned to the assignee hereof. a

As illustrated and described in the previously identified patent, the thermal current responsive member 70 is preferably operable not only in response to the heating effect of the current passing therethrough, but is also operable under the control of electro-magnetic means for effecting disengagement of the companion relatively movably such that, as here shown, the electro-magnetic means is energized by the current which passes through the said thermal current responsive member. For this purpose, an electro-magnetic member 90 is fixedly secured, in any suitable manner, on the strip 70 and a companion rigid armature 92 is secured to the movable contact member 34 and is disposed in spaced confronting relation to the electromagnetic member 90. The electro-magnetic member 90 and the armature 92 operate substantially in the same way as corresponding mechanism in the previously identified patent.

While I have illustrated and described the arc blowout means of my invention in connection with the separable contacts of a circuit breaker, it will be understood that it is not limited to use with a circuit breaker, and that it is adaptable for use in other types of electric control devices provided with separable contacts.

While I have shown and described the preferred embodiment of my invention, it will be understood that various changes may be made in the present invention without departing from the underlying idea or principle of the invention, within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. An automatic circuit breaker comprising an insulated casing provided with portions which define an arcing chamber and an adjacent chamber for the circuit breaker mechanism, a stationary contact provided in said arcing chamber and a vent defined therein and spaced from said stationary contact, a portion of said casing extending into said arcing chamber and constituting a baflie for directing arc gases to said vent, portions of said casing defining a passageway between said chambers, a movable switch member extending through said passageway from said adjacent chamber into said arcing chamber and provided with a movable contact for engagement with said stationary contact, and an arc blow-out membermounted on said battle and positioned thereby in oppositlon to said passageway for directing arcs which may be drawn between said contacts away from said passageway and toward said vent.

2. An automatic circuit breaker comprising an insulated casing provided with portions which define an arcing chamber and an adjacent chamber for the circuit breaker mechanism, a stationary contact provided in said arcing chamber and a vent defined therein and spaced from said statlonary contact, a portion of said casing extending into said arcing chamber and constituting a bafile for directing are gases to said vent, portions of said casing defining a passageway between said chambers, a movable switch member extending through said passageway from said adjacent chamber into said arcing chamber and provided with a movable contact for engagement with said stationary contact, and an arc blow-out member mounted on said baflie and positioned thereby in opposition to said passageway for directing arcs which may be drawn between said contacts away from said passageway and toward said vent, said blow-out member having spaced poles adjacent the engaged contacts for establishing a magnetic field to which the arc is drawn, and said member extending in the direction of the disengaging movement of said movable contact, from said poles thereof, toward said vent.

3. An automatic circuit breaker comprising an insulated casing provided with portions which define an arcing chamber and an adjacent chamber for the circuit breaker mechanism, a stationary contact provided in said arcing chamber and a vent defined therein and spaced from said stationary contact, a portion of said casing extending into said arcing chamber and constituting a battle for directing arc gases to said vent, portions of said casing defining a passageway between said chambers, a movable switch member extending through said passageway from said adjacent chamber into said arcing chamber and provided with a movable contact for engagement with said stationary contact, and an arc blow-out member mounted on said bafile and positioned thereby in opposition to said passageway for directing arcs which may be drawn between said contacts away from said passageway and toward said vent, said blow-out member having spaced poles adjacent the engaged contacts for establishing a magnetic field to which the arc is drawn, and a linear porable contacts 30 and 32, and the arrangement is preferll tion of said member extending in the direction of the disengaging movement of said movable contact toward said vent.

4. In a circuit breaker, an insulated casing in which there is defined a pair of chambers and a passageway therebetween, one of said chambers constituting an arcing chamber and the other chamber having provision to mount the breaker mechanism therein, a vent for said arcing chamber defined in said casing substantially in opposition to said passageway, a stationary contact positioned in said arcing chamber between said passageway and said vent, a movable switch member extending from said other chamber into said arcing chamber for engagement with and disengagement from said stationary contact to close and open the breaker, respectively, and an arc blow-out member mounted in said arcing chamber, said blow-out member having one end adjacent said stationary contact and extending therefrom in the direction of disengagement of said movable switch member and toward said vent.

References Cited in the file of this patent UNITED STATES PATENTS 1,820,927 Whitney et al. Sept. 1, 1931 2,065,356 Von Hoorn Dec. 22, 1936 2,268,336 Jackson et al. Dec. 30, 1941 2,340,682 Powell Feb. 1, 1944 2,467,937 Jackson Apr. 19, 1949 2,629,035 Yingst Feb. 17, 1953 

